1. Field of the Invention
The present invention relates to a bag which is suitable for use in an air bag apparatus that is activated when a vehicle rapidly decelerates. The bag expands toward a vehicle occupant when a gas is introduced therein.
2. Description of the Related Art
In an air bag apparatus, such as one that is mounted on a steering wheel, an activating device is activated when a vehicle rapidly decelerates. The activating device ignites a detonator disposed within an inflator so as to cornbust a gas generating material with a explosion inducing agent, thereby producing a large quantity of a gas. The gas thus produced flows into a bag which is stored within a pad in a folded state on the side in which the inflator faces an occupant. Thus, the bag expands and unfolds toward the occupant and breaks the pad so as to be interposed between the steering wheel and the occupant.
Conventionally, this type of bag is provided with circular ventilating apertures (hereinafter called "vent holes") defined thereof on the side opposite that of the occupant. The gas, which flows into the bag at high speed and in large quantity, is discharged by a predetermined amount through the vent holes so as to maintain the bag in an expanded state under a predetermined internal pressure.
However, the gas discharges from the vent holes even before the bag fully expands, i.e., during the expansion of the bag. It is therefore necessary to take desired measures such as a measure for causing directions to exhaust the gases from the inflator to face toward the occupant in large numbers to avoid a delay of the expansion of the bag, a measure for increasing the amount of a gas generating material to be inserted into the inflator.